Electronics > Power/Renewable Energy/EV's

hypersonic MHD?

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I thought that was interesting. The basic idea is a magnetohydrodynamic generator that is optimized for peak power production, rather then regulated and steady power production.

It would seem that the MHD principle has no bottle neck for peak energy.

Interestingly enough I got some flux in the air acetylene brazing torch tip last night while I was making some hardware to mount a PCB on, and it shows the effect of 'loading' plasma with ions, turning a normally blue flame into a torquise flame because of whatever salts there are in silver brazing flux.

Also interesting as this type of MHD the Chinese have made can explode if the "boiler" fails  ;D.



This type of technology certainly feels like a episode of star gate. I suspect the electrodes get destroyed pretty quick, and the machine is a very long way off from being a reciprocating device like a modern engine. Slightly more tame version of the flux compression generator, and you also need some helva strong magnets.


--- Quote ---This type of technology certainly feels like a episode of star gate.
--- End quote ---
Not really. It's simple physics. There is a good reason why there is no real use for continuous MHD in power transformation.

--- Quote ---The reasons for limited power generation are proposed as: low conductivity of RF discharge; large touch resistance between MHD electrode and plasma; strong current eddies due to flow boundary layer.
--- End quote ---
Yep, it's right there : too much loss with air, or in fact, any non-metals.
MHD is in use for flow sensors, where efficiency does not matter.

--- Quote ---(RF) discharge (6 MHz, maximum continual power output of 200 W) was adopted to ionize the Mach number 3.5 (650 m/s), 0.023 kg/m3 airflow. In a MHD channel of 16 mm × 10 mm × 20 mm, MHD open voltage of 10 V is realized in the magnetic field of 1.25 T, and power of 0.12 mW is extracted steadily and continuously in the magnetic field of 1 T.
--- End quote ---
Hilarious efficiency. Probably like 8 orders of magnitude worse than Hydrogen fuel cells with electrolyzers :-DD :-DD That's a real feat !

The episode with the replicators trying to ion beam atlantis, was very similar to taking energy out of a plasma beam, so that reminded me of some kind of advanced MHD generator, which took a portion of the energy from the ion beam being shot through the stargate the power the shields of the weapons satellite.

Out of all the types of generators that you could put in a TV show, I think a super sonic plasma exploder is #2 behind the EFCG. Maybe #3 if you consider back to the future, because lightning is also pretty awesome.

SG1 had its stargate powered by event horizons, lightning. Atlantis had been powered by solar panels by the dying star in that one episode (pretty cool), metrological life forms too. Could have been a MHD type effect from the polar vortrex formed near the event horizon of a black hole that was powering the gate, with the time dilatation episode. The whole 'parasitic effect = 10 yottawatt generator' thing was cool.

Does anyone think its possible to make like a butane powered spot welder using MHD technology?

The requirement would be between 1-500 joules of energy. The idea being there is a combustion chamber infront of a MHD gen, that you fill with butane, propane, alcohol, gasoline, etc and ignite in order to power a spot weld maybe with atomoised ions by using a ultrasonic mister with some ionic salt solution. Like a potato gun kinda. I think the regulation requirements are alot less then the high tech applications involving radars and lasers. I wonder if its possible to do with just a switch and no super capacitors.

Or a even bigger one, meant for welding rebar, or railroad tracks together. You would still need a monitor circuit to verify the weld parameters were met, if it was to be really used in industry.

You certainly could do it; physics doesn't prohibit it. It's just that the efficiency will be very low. A spot welder is a particularly bad application because it demands low impedance and short time duration - so either you need to save energy over time, and charge up a battery, or you need to have an absolutely massive power source whose output is completely wasted 99.9999% of the time.

To make the kind of spot welds used in phone/laptop battery packs, you might need a 2 MW torch to make a 1500W peak (1500A, 1V) spot weld (going off f4eru's cited numbers). This is an example of a 1 MW food oil burner:

A YouTuber will probably do it eventually, but I don't expect it would get many views.

One can speculate on MHD detonation acceleration as an alternative to steady state MHD generation, but I don't really know what I'm talking about in that department. If you do that, please don't do it around me.


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